Typical nozzles primarily increase the gallons per minute delivered by enlarging the primary delivery orifice on the nozzle. It is desirable in practice to increase or decrease the gallons per minute delivered by a sprinkler whenever multiple sprinklers are used within the same piping or valved delivery system that applies water to a given area which requires different patterns or radius from individual sprinklers within the system. The term "matched precipitation" refers to a system comprised of sprinklers within a particular system delivering about the same amount of water to a given area in the same amount of time regardless of the individual radius or areas the individual sprinklers are required to service. This means that a sprinkler set for a 180 degree radius (half circle) on the same circuit as a sprinkler set for a 90 degree radius, needs to deliver twice as much water as the sprinkler set for 90 degrees over the same amount of time. Since these sprinklers are on the same circuit there is no practical means of increasing or decreasing an individual sprinklers operating time.
The current method of attaining matched precipitation is by increasing the nozzle(s) orifice size to incrementally increase the discharge in gallons per minute. For example, a 90 degree sprinkler could use a nozzle set to deliver one gallon per minute, a 180 degree sprinkler could use a nozzle set to deliver two gallons per minute, a 270 degree sprinkler could use a nozzle set to deliver three gallons per minute, and a 360 degree sprinkler could use a nozzle set to deliver four gallons per minute by making the orifice correspondingly larger on the each individual sprinkler nozzle. This method achieves a poor degree of success, in fact, because the distance the nozzles throw the water stream increases as the gallons per minute increases thereby increasing the radius. Mechanical stream interfering devices are currently employed to compensate for the distance (radius) increase, but at great expense of application uniformity. Mechanical interfering devices (commonly screws that extend into the water stream) produce unpredictable results and destroy the physical characteristics of the water stream. Uniformity of application is the goal of matching precipitation rates. Consequently, a need exists for a sprinkler nozzle which can uniformly distribute water without increasing the distance thrown.